Multiprotocol Label Switching (MPLS) enables efficient delivery of a wide variety of differentiated, end to end services. Multiprotocol Label Switching (MPLS) traffic engineering (TE) provides a mechanism for selecting efficient paths across an MPLS network based on bandwidth considerations and administrative rules. Each label switching router maintains a TE link state database with a current network topology. Once a path is computed, TE is used to maintain a forwarding state along that path.
In the case of deployment of MPLS Resource Reservation Protocol (RSVP) Inter Domain Traffic Engineering Label Switched Paths (TE LSPs), RSVP HELLO messages are initially exchanged between RSVP-capable routers such that an RSVP neighbor relationship is established.
To efficiently detect a nodal failure or restart, the HELLO messages are exchanged at a fairly regular interval on a per-neighbor basis. Having multiple interfaces/neighbors increases the number of HELLO messages that need to be exchanged, resulting in a significant control plane overhead. This control plane overhead is reduced by reducing the interval between HELLO message exchanges. However, this increased interval may result in a delayed failover (resulting in dropped traffic) or a delay in recognizing that an apparently failed node is back in operation (resulting in inefficient use of the restored node).
Within the context of some Point to Multi-Point (P2MP) Networks, various Border Gateway Protocol (BGP) extensions and procedures allow the use of Bidirectional Forwarding Detection (BFD) to provide fast detection and failover for upstream faults such as neighboring node failure. However, if an apparent neighboring node failure is simply a restart of the neighboring node, the propagation of upstream fault information will unnecessarily result in the removal of the restarting node from service for an extended period of time.